Twin Research and Human Genetics

Abstract Aim: To translate, culturally adapt, and psychometrically validate the Arabic version of the REAP-S among Arabic speaking young adults using Confirmatory Factor Analysis (CFA) and Rasch Measurement Theory (RMT). Design: A cross-sectional methodological psychometric validation study. Methods: The study included 500 undergraduate and postgraduate nursing students recruited from Saudi universities during the 2025-2026 academic year. The REAP-S was translated into Arabic using standardized forward backward translation procedures and cross-cultural adaptation guidelines. Participants completed the Arabic REAP-S through an online self-administered questionnaire. Construct validity was evaluated using CFA with robust estimators, assessing the Comparative Fit Index (CFI), Tucker-Lewis Index (TLI), Root Mean Square Error of Approximation (RMSEA), and Standardized Root Mean Square Residual (SRMR). Rasch Measurement Theory was applied to examine item fit, response category functioning, person item targeting, and person reliability. We assessed internal consistency using Cronbach's alpha and the Rasch Person Separation Index (PSI). Results: Psychometric analyses included 490 participants with a median age of 20 years (IQR = 19-22), of whom 54.1% were female. CFA supported the hypothesized one-factor structure and showed good model fit (CFI = 0.984, TLI = 0.978, RMSEA = 0.076, SRMR = 0.061). Standardized factor loadings ranged from 0.429 to 0.768, and internal consistency was good (Cronbach's = 0.863). Rasch analysis confirmed the scale's unidimensionality, with satisfactory person reliability (Expected A Posteriori [EAP] = 0.872; Weighted Likelihood Estimate [WLE] = 0.848). All items demonstrated acceptable infit and outfit mean square statistics (0.826-1.311 and 0.866-1.283, respectively), with ordered response thresholds and adequate person-item targeting. Overall, the Arabic REAP-S effectively discriminated between different levels of dietary behavior among Arabic-speaking young adults. Conclusion: The Arabic REAP-S demonstrated strong validity and reliability, supporting its unidimensional structure and appropriate psychometric performance. Evidence from both CFA and Rasch analysis confirmed acceptable model fit, good internal consistency, and adequate item functioning. The instrument provides a brief and practical tool for assessing dietary behaviors among Arabic-speaking young adults in clinical and research settings. Implications for the Profession and/or Patient Care: The Arabic REAP-S provides nurses and other healthcare professionals with a brief, standardized tool for rapidly assessing dietary behaviors and identifying individuals at nutritional risk. Its integration into routine clinical and community practice may support early dietary screening, guide nutrition education, and strengthen evidence based preventive care for diet related chronic diseases. Keywords: Arabic REAP-S; Dietary Screening; Confirmatory Factor Analysis; Rasch Measurement Theory; Construct Validity; Young Adults.

Objective: Overweight and obesity in childhood and adolescence are major risk factors for health problems across the lifespan. This manuscript reports the current prevalence of overweight and obesity among children and adolescents aged 4-17years living in Germany and compares them with previous population-based results. Methods: A representative, cross-sectional sample of 4-17-year-olds was drawn following a multistage sampling process. Analyses are based on weight and height of 3,978 individuals measured in the field by trained test instructors between 2023-2025. Overweight and obesity classification was defined using age- and sex-specific body-mass-index percentiles. To allow for comparability of prevalence estimates derived from previous assessment waves and other panel studies dating back to 2005, an alignment factor was derived using an inverse probability of participation weighting approach. Together with sampling weights, the alignment factor was applied to obtain current, representative prevalence estimates of overweight and obesity. Results: The aligned, weighted prevalence of overweight and obesity was 16.1% (95%CI[14.5-17.9%]), whereas prevalence of obesity was 6.7% (95%CI [5.5-8.1%]). Age- and sex-specific prevalence rates are reported and compared to previous waves. Conclusions: The current prevalence of overweight and obesity in children and adolescents aged 4-17 years living in Germany remains stable over the past two decades.

Purpose: Impaired balance and fall risk in individuals with respiratory conditions highlight the importance of respiratory-postural integration during upright activity. However, breathing and postural control are often studied separately, limiting understanding of their interaction. Singing imposes concurrent ventilatory and trunk control demands, yet respiratory-postural responses during standing singing remain unclear. We examined the effects of vocalisation and tempo on respiratory-postural responses during standing, and whether age and singing experience moderated these responses. Methods: Eighty healthy younger (18-35yr; n=35) and older ([&ge;]60yr; n= 45) adults completed rhythmically paced speaking and singing tasks at slow, normal, and fast tempos while standing on a force platform. Respiratory rate (RR), mediolateral and anteroposterior sway, peripheral oxygen saturation, and perceived breathlessness were measured. Generalised estimating equations assessed vocalisation, tempo, and their interaction, with moderation by age and singing experience. Results: RR showed a vocalisation x tempo interaction (p<.001), with higher RR during slow speaking and greatest increases during fast singing. Singing increased postural sway relative to speaking, particularly mediolaterally (p<.001), with tempo-related increases in anteroposterior sway (p<.001). Older adults exhibited greater postural sway overall (p values[&le;].040) but similar task-dependent modulation to younger adults. Singing experience attenuated RR increases during fast singing (p=.033) and was associated with greater mediolateral sway (p=.004). Perceived breathlessness increased with tempo but was not associated with vocalisation; SpO2 was unchanged. Conclusions: Standing singing was associated with tempo-dependent respiratory and postural responses. Age and singing experience showed distinct associations with these responses. Task-dependent respiratory-postural coordination appeared preserved among participants.

Importance. Anorexia nervosa (AN) is a severe metabo-psychiatric disorder with heterogeneous outcomes and elevated mortality. Characterizing severity trajectories may improve early risk stratification and targeted intervention. Objective. To identify AN severity trajectories using a register-based severity index (AN-RSI) and examine their associations with polygenic scores (PGS), preceding (prior to AN diagnosis) as well as subsequent (5 years post AN diagnosis) psychiatric and somatic disorders. Design. Population-based cohort study. Setting. Nationwide study in Denmark. Participants. Individuals born between 1969 and 2013 with diagnosed AN (N = 9,534 individuals). Genetic data were available in a subsample comprising 5,126 individuals. Exposures. Forty-one PGS indexing traits relevant to AN, and psychiatric and somatic disorders prior to AN diagnosis. Main Outcomes and Measures. The main outcomes of interest were the AN-RSI trajectories and psychiatric and somatic disorders 5 years post AN diagnosis. Results. Three trajectories were identified: "low and stable" (32.6%), "medium and stable" (53.5%), and "high increasing" (14.0%). The "low and stable" group was used as the comparison group for all analyses. Each 1 standard deviation (SD) increase in AN PGS corresponded with 13% greater odds of following the "high increasing" trajectory. Increases in BMI and attention-deficit/hyperactivity disorder PGS corresponded with 15% and 14% lower odds of following the "high increasing" trajectory, respectively. No preceding psychiatric or somatic disorders were significantly associated with trajectory assignment. In contrast, psychiatric and somatic disorders were more likely to occur subsequent to an AN diagnosis in those in the "high increasing" trajectory with odds ratios (OR) ranging between 1.73 and 3.81 for psychiatric disorders and between 1.61 and 5.38 for somatic disorders with a notable exception of obesity which showed a lower OR of 0.27. Conclusions and Relevance. Our findings hold significant clinical relevance by demonstrating that individuals with AN follow distinct severity trajectories that have different genetic risk as measured by PGS and clear differences in post-diagnosis morbidity patterns but no discernable differences in pre-diagnosis psychiatric or somatic morbidity. As the eating disorders genetics field progresses, incorporating PGS into comprehensive assessments at first presentation may aid in early identification, personalized intervention, and resource allocation for individuals at higher risk of developing a severe illness trajectory.

Introduction: Nursing students experience stress arising from demanding academic requirements and emotionally challenging clinical placements, which may affect wellbeing, learning, and programme retention. This study explored perceptions of stress, its impacts, and coping experiences within undergraduate nursing education among nursing students and educators in New Zealand. Methods: A qualitative descriptive study was conducted with six undergraduate nursing students and six nurse educators at a New Zealand university. Data were collected through semi-structured interviews and analysed using inductive reflexive thematic analysis, with interpretation informed by the Transactional Model of Stress and Coping. Results: Three themes were identified: stress from multiple sources, stress shaping wellbeing and learning, and navigating stress through appraisal and coping. Stress arose from academic, clinical, personal, and social demands and affected academic engagement, health, and relationships. Participants described varied responses to stress, including different appraisals of challenging situations and coping strategies such as peer support, self-care, and use of institutional resources. Conclusion: Stress in nursing education reflects a dynamic interaction between individual appraisal, coping resources, and educational and interpersonal contexts. Although findings are limited to one institution, they highlight the importance of accessible, flexible, and culturally responsive support and of addressing modifiable educational stressors alongside strengthening students' coping resources.

Background: Unpaid caregiving is a recognised social determinant of health, yet most research treats it as a fixed exposure measured at a single time point, and little is known about how patterns of caregiving transitions relate to health behaviours. Methods: Secondary analysis of the UK Household Longitudinal Study (waves 2 to 13, approximately 2010 to 2023; n=25,049). Latent class analysis was applied to binary caregiving status across 12 waves to identify caregiving trajectories. Associations between trajectories and four health behaviours (physical inactivity, fruit and vegetable consumption, problematic drinking, current smoking) at waves 7 to 13 were estimated using logistic and linear regression, adjusting for sociodemographic, health and baseline behavioural confounders. Results: An eight-class solution identified a non-caregiving class comprising 62.9% (n=15,760) of the sample. Among caregivers (n=9,289), trajectories were Temporary (20.0%), Former-short (20.2%), Former-long (10.9%), Emerging-short (15.4%), Emerging-long (11.6%), Long-term (15.7%) and Recurrent (6.3%). In fully adjusted models, Recurrent caregivers had higher odds of smoking (OR=1.67, 95%CI: 1.17 to 2.40) compared with non-caregivers but lower odds of physical inactivity (OR=0.65, 95%CI: 0.53 to 0.81) and problematic drinking (OR=0.75, 95%CI: 0.59 to 0.94). Associations for other trajectory classes were largely attenuated after adjustment. Conclusion: The pattern and timing of caregiving transitions are an under-explored dimension of the caregiving experience. Recurrent caregivers had a distinctive profile, with elevated smoking but lower physical inactivity and problematic drinking. Recurrent caregiving should be recognised alongside intensity and duration, and support systems better equipped for people who move into and out of care repeatedly.

Aims/hypothesis Higher body mass index (BMI) is associated with higher levels of HbA1c and glucose in conventional observational studies from sub-Saharan Africa, but its causal relationship in this population has not been explored. Mendelian randomization (MR) which leverages genetic variants can strengthen causal inference. However, its application in African ancestry populations is limited. The aim of this study was to determine whether causal effects of BMI on glycated haemoglobin (HbA1c) and random glucose differ between African and European populations. Methods We used two-sample MR to estimate the effects of BMI on HbA1c and random glucose in adults of African and European ancestries. We conducted a cross-ancestry BMI genome-wide association study (GWAS) from the Africa-Wits International Network for the Demographic Evaluation of Populations and Their Health (INDEPTH) Partnership for Genomic Studies (AWI-Gen) dataset of African adults (N=10,476) and the largest BMI GWAS in Europeans (N~700,000). From the cross-ancestry GWAS we identified 428 independent genome-wide significant variants and of those, 363 single nucleotide polymorphisms (SNPs) had consistent direction of effect in both Africans and Europeans. These variants were then used as genetic instruments to proxy BMI for both Africans and Europeans. Primary outcome data for African and European populations were obtained from UK Biobank summary statistics for HbA1c (5,790 Africans and 400,825 Europeans) and random glucose (5,750 Africans and 314,916 Europeans), with additional results for HbA1c from the MAGIC multi-ancestry GWAS comprised of Ugandan individuals (N=4,441), African Americans (N= 6,647), and Europeans (N=146,806). Main analyses used the inverse variance weighted (IVW) method, with sensitivity analyses conducted using MR-Egger, weighed median and weighted mode approaches. Results The main IVW analyses in UK Biobank provided support for higher BMI causally increasing HbA1c levels in both Africans (0.26 SD higher HbA1c per 1 SD BMI, 95% CI 0.07, 0.45) and Europeans (0.27 SD higher HbA1c per 1 SD BMI, 95% CI 0.22, 0.32). UK Biobank main analyses also supported higher BMI increasing random glucose in Africans (0.21 SD higher mean glucose per 1 SD BMI, 95%CI 0.03, 0.37) and Europeans (0.15 SD higher mean glucose per 1 SD BMI, 95%CI 0.12, 0.18). Sensitivity analyses suggested these results were not biased by unbalanced horizontal pleiotropy. Results from MAGIC also showed that higher BMI causally increased HbA1c in Europeans (0.04% higher HbA1c per 1 SD BMI, 95% CI 0.02, 0.05), though results for African Americans (0.01% higher HbA1c per 1 SD BMI, 95% CI -0.05, 0.07) and Ugandans (0.02% lower HbA1c per 1 SD BMI, 95% CI -0.10, 0.05) spanned the null. Conclusion/interpretation We have found broadly similar effects of BMI on HbA1c and random blood glucose in African and European populations. However, much larger GWAS of glycaemic traits in African and other non European populations are needed to strengthen causal inference and support equitable translation of these findings. The method that we have used to obtain identical strong genetic instrumental variables (IVs) for both European and African populations may have value for other MR studies interested in exploring differences in effects between different population groups.

Abstract Unplanned Extubation is a frequent adverse event in Neonatal Intensive Care Units (NICUs), that is associated with increased morbidity, prolonged hospitalization and financial costs. Evidence suggests that unplanned extubation (UE) is preventable through the management of its risk factors. Many modifiable UE risk factors are directly related to nursing care, thus empowering nurses through education can improve neonatal safety outcomes. This study aimed to evaluate the effectiveness of a structured educational intervention in improving nurses knowledge and practices related to UE in NICUs. A quasi-experimental pretest-posttest study was conducted in two tertiary hospitals in northern Jordan. One hospital is university-affiliated and one is governmental hospital. Participating Nurses in the selected settings received a four-week multimodal educational intervention related to UE. The intervention comprised of face-face session, WhatsApp-based educational messages, educational videos and placement of a poster in the NICU. Knowledge and practices of 58 nurses were assessed at baseline, post intervention and one month later using a validated questionnaire and direct observation. A baseline rate of UE was also measured in both settings with rate of 5 events per 100 ventilator days in the university-affiliated compared to 32 events per 100 ventilator days in governmental hospital. Repeated-measures and mixed-design ANOVA revealed significant improvements in nurses knowledge in both settings with a large effect size (p{superscript 2} = .60). Also, the observed preventive practices scores also improved significantly and remained elevated at one-month follow-up (p{superscript 2} = .50). Older age was associated with lower baseline knowledge, though this was diminished post study intervention. Whereas no demographic variables were associated with practice scores. The high rates of UE highlight the need for quality improvement. Study findings suggest that UE-focused education is a feasible and cost-effective strategy for strengthening neonate nurses competencies regarding safer care for mechanically ventilated neonates in the NICUs.

Background: Thinness-oriented body ideals are well described among young Japanese women, but variation in visual and numerical ideals by sex, age, and current BMI remains unclear. Methods: We analysed an unweighted web-panel sample of 27,359 Japanese adolescents and adults aged 15-69 years from the Survey of Body Shape and Health Awareness in Japanese People, a cross-sectional web-based survey. Current and ideal BMI were derived from self-reported height and weight, and visual orientation from ideal versus perceived current silhouette. Adult BMI-stratified analyses included participants aged 20-69 years. Findings: Among 27,359 participants (10,094 men and 17,265 women), relative thinness-oriented indicators increased with current BMI in both sexes. Among normal-weight women, 74.7-83.7% selected a smaller ideal silhouette and 79.2-91.2% reported an ideal BMI lower than current BMI. These indicators were also present among underweight women aged 20-29 years (44.9% and 43.4%, respectively), but declined with age. Most underweight men reported weight-gain-oriented ideals. Fine stratification showed that thinness-oriented ideals among women were common in low-normal and mid-normal BMI strata. Interpretation: Body-size ideals differed by sex, age, and current BMI. Thinness-oriented ideals among women extended beyond obesity and young adulthood, whereas underweight men generally preferred a larger body. Longitudinal and behavioural studies are needed. Funding: Cabinet Office of Japan Strategic Innovation Promotion Program (SIP), "Inclusive Community Platform" (grant no. SIPCP23C02).

Sex and gender are distinct but intertwined determinants of health. Both adherence to and deviation from gender norms carry consequences for health, yet gender's contribution to disease risk beyond binary sex remains largely unexplored. As gender is organized around sex from its developmental origins, masculine and feminine health behaviors can be defined by how males and females behave collectively. Individuals vary in how closely they align with these norms, defining a biopsychosocial gender spectrum. Here, we used machine learning to reconstruct population-specific masculine and feminine behavioral norms, yielding a continuous Index of Gendered Life-domains (IGL) in 301,113 UK Biobank participants. In sex-stratified analyses of body and brain health phenotypes, masculine behavioral profiles were associated with greater physiological load and cardiometabolic disease risk, and feminine profiles with higher trait anxiety and musculoskeletal vulnerability. Sex-IGL incongruence predicted state-like psychiatric symptoms and severe mental health diagnoses. An intersectional approach revealed differences in gendered behaviors and their health associations across ethnic groups, demonstrating that gender measurement must be sensitive to sociocultural context to characterize health risk in diverse populations. These findings establish gender as a socioculturally embedded determinant of health whose health associations go beyond binary sex.

PURPOSE: Women with metastatic breast cancer (MBC) are at risk of developing financial toxicity due to prolonged treatment. Resilience has been identified as a key protective factor associated with better quality of life among cancer populations. However, it is unknown if resilience is associated with financial toxicity. We sought to examine the relationship between resilience and financial toxicity among women with MBC and explore whether socioeconomic factors moderate this association. PATIENTS AND METHODS: Our sample included 209 women with MBC who completed self-reported questionnaires of the Resilience Scale Specific to Cancer (RS-SC) and the Comprehensive Score for Financial Toxicity (COST). Participants (n=2) with missing data were excluded from analysis. We conducted multiple linear regression to examine the association of resilience with financial toxicity. Interaction terms were used to test moderating effects of age (18-39, 40-64 and > =65 years), race, education, health insurance, household income and employment status. RESULTS: Of the sample, 56.5% were aged 40-64 years, 76.6% were White, and 79.9% had a college or master degree or above. Women reported moderately high resilience with mean RS-SC score of 34.49 (SD = 6.67), and moderate financial toxicity (mean COST score =21.01 [SD = 10.51]). Adjusting for covariates, higher resilience was linked to better financial well-being (b = 0.37, SE= 0.11, 95% CI [0.14, 0.59], P < 0.01). Age, education and health insurance moderated this relationship, with resilience more strongly associated with better financial well-being among those aged 40-64 years, with college/master degree or above and private insurance. Race, household income, and employment status did not moderate the association between resilience and financial toxicity. CONCLUSION: Women with MBC who reported higher resilience are more likely to experience better financial well-being, but the strength of this association varied by socioeconomic factors. Further research is needed to confirm these findings. Our results have important implications for incorporating resilience into financial toxicity interventions and tailoring such interventions based on individual socioeconomic characteristics.

Purpose: The internship period is a critical stage for nursing students to develop professional values. This study aimed to investigate the current status of professional identity among nursing interns, analyze the effects of social support, perceived stress, psychological resilience, and career adaptability on professional identity, and explore the mediating role of career adaptability between social support and professional identity, so as to provide empirical evidence for enhancing professional identity and optimizing nursing talent training systems. Methods: Using convenience sampling, 407 nursing interns from a tertiary hospital in Quanzhou were selected as participants from May to July 2025. Data were collected using a general information questionnaire, the Social Support Scale, the Perceived Stress Scale, the Psychological Resilience Scale, the Professional Identity Questionnaire for Nursing Students, the Career Adaptability Scale, and the Questionnaire for Nurse Intention to Retention Employed. SPSS 26.0 was used for reliability analysis, descriptive analysis, independent samples t-test, one-way ANOVA, Pearson correlation analysis, and multiple linear regression analysis. The PROCESS macro was employed to test the mediating effect. Results: The total score of professional identity among nursing interns was (61.74{+/-}11.08), with 73.5% showing moderate professional identity. Parents' attitude toward nursing, reasons for choosing the profession, personal attitude toward the major, and employment intention showed statistically significant differences in professional identity scores (p<0.05). Pearson correlation analysis revealed that professional identity was significantly positively correlated with social support (r=0.474), psychological resilience (r=0.389), and career adaptability (r=0.609) (p<0.01), and significantly negatively correlated with perceived stress (r=-0.378) (p<0.01). Multiple linear regression analysis indicated that career adaptability ({beta}=0.309, p<0.001) and social support ({beta}=0.383, p<0.001) were significant positive predictors of professional identity, whereas reasons for choosing the profession ({beta}=-3.603, p=0.001) and employment intention ({beta}=-7.116, p<0.001) were significant negative predictors. The model explained 49.2% of the variance in professional identity. Mediation effect analysis showed that career adaptability played a partial mediating role between social support and professional identity, with a mediation effect value of 0.288 (95% CI: 0.221-0.363), accounting for 40.2% of the total effect. Conclusions: Nursing interns' professional identity is at a moderately high level. Social support and career adaptability are positive influencing factors. Career adaptability plays a partial mediating role between social support and professional identity; social support indirectly enhances professional identity by strengthening career adaptability.

Background: Although point-of-care testing is the standard method for inpatient glucose monitoring; it is associated with patient discomfort and late detection of dysglycaemic events. Continuous glucose monitoring (CGM) may improve glycaemic management; however, limited staff education and experience among may hinder its implementation. Aim: To investigate experience, perceptions and training needs on CGM use among inpatient nursing staff across diverse hospital wards. Methods: This is a single-centre, 38-item online survey recruited inpatient nurses in a hospital in the UK. Participants were invited via the e-newsletter and posters; the survey remained open for five months. Results: Nineteen nurses reported positive perceptions of inpatient CGM. Most considered CGM reliable (77.8%) and preferred CGM combined with POCT (66.7%). Views on its impact on workload and patient-room entries were mixed (30% agreed, 30% disagreed). Training needs included sensor placement (92.9%) and alarm management (78.6%). Conclusion: Nurses viewed CGM favourably but highlighted important training needs for inpatient use.

Health inequalities are often examined through single axes such as class or ethnicity, obscuring how these dimensions interlock. This study applies a longitudinal intersectional approach to examine physical and mental health trajectories across five generations in the UK. We analysed 14 waves of the UK Household Longitudinal Study (2009-2024) using longitudinal Multilevel Analysis of Individual Heterogeneity and Discriminatory Accuracy (MAIHDA). We modelled SF-12 physical and mental health trajectories for 398 intersectional strata defined by gender, ethnicity, occupational class, and generation. Physical health inequalities widened with age, consistent with cumulative disadvantage, while mental health inequalities were more evident among later-born cohorts. The 'Boomer' generation exhibited a relatively flat mental health trajectory across its observed age range. In contrast, 'Generation Z' had lower predicted mental health, particularly among White British women with no work history - a group with poorer predicted trajectories than their South Asian peers. Our study shows how health inequalities are structurally differentiated by cohort and intersectional position. Policy responses should support proportionate universalism, combining broad population-level support with intensified action for groups showing poorer health.

Financial well-being (FWB) encompasses objective and subjective financial status and may influence health. We developed and validated a parsimonious FWB index using data from 23,006 Health and Retirement Study (HRS) participants aged 50 years and older from 2006 to 2022. The FWB-5 Index was derived using correlated two-factor confirmatory factor analysis accounting for household clustering. Indicators included household wealth, household income-to-poverty ratio, monthly financial strain, satisfaction with one's financial situation, and perceived financial mastery. We assessed convergent and discriminant validity using the Consumer Financial Protection Bureau Financial Well-Being (CFPB-FWB) Scale and Satisfaction with Life Scale, respectively. Associations with pre-baseline socioeconomic factors and subsequent depressive symptoms and health conditions were examined to assess construct and predictive validity. Model fit indices supported the two-factor structure (robust comparative fit index = 0.99; robust root mean square error of approximation = 0.05). Correlations were stronger with the CFPB-FWB Scale (Spearman P = 0.80) than with life satisfaction (Spearman P = 0.43). Associations with socioeconomic factors and subsequent health outcomes were in the hypothesized directions. These findings support the FWB-5 Index as a parsimonious measure for examining financial well-being and its associations with health across HRS waves, including those predating the CFPB-FWB Scale.

BackgroundEarly-life air pollution exposure has been associated with childhood asthma, but its relative contribution is poorly characterised in cohorts with repeated indoor measurements. Short sampling windows and seasonal bias limit how well any single measurement can represent cumulative exposure. ObjectiveTo evaluate the association between early-life indoor and outdoor pollutant exposure from birth to 18 months and asthma development at ages 7, 12, and 18 years, while testing potential exposure-exposure and gene-environment interactions. MethodsIn the COPSAC2000 birth cohort (n = 411), indoor PM2.5, black carbon, NO2, NOx and VOCs, and modelled outdoor PM2.5, NO2 and NOx, were assessed at 6, 12 and 18 months of age. Indoor metrics were corrected for pump-flow drift and seasonal bias via a Gaussian process with a periodic kernel. Hierarchical Bayesian logistic regression(HBLR) and calibrated random forests (CRF) were evaluated using stratified nested cross-validation for discrimination using AUC-ROC, Calibration using integrated calibration index (ICI), and Brier skill scores. Exposure-exposure and gene-environment interactions were quantified via Shapley interaction indices. ResultsDiscrimination was weak at all endpoints with test AUC-ROC: 0.58-0.67, BSS near zero (0.012 to 0.05) and ICI: 0.043-0.061 for random forest and AUC-ROC 0.53-0.61, BSS equal to zero and ICI: 0.054-0.067 for hierarchical Bayesian logistic regression (HBLR). No pollutant reached a highest density interval excluding OR = 1. The polygenic risk score(PRS) was the only term non-null at all three ages in the adjusted models. While gene-environment interactions were detected, effect sizes were negligible and statistically indistinguishable from zero. SignificanceWhere ambient pollution is low, cumulative early-life exposure adds little to long-term asthma prediction beyond genetic and contextual factors, and an improved exposure correction does not uncover an effect. ImpactRepeated bedroom measurements across infancy are rare, and short sampling windows make them hard to read as cumulative exposure. We corrected measured concentrations for pump-flow drift and for seasonal sampling bias on the pollutants and used two complementary machine learning models to predict interaction and risk. In this low-exposure Danish cohort, genetic risk and residential context dominated, and the measured pollutants added almost nothing to the asthma risk at 7,12 and 18 years. These null results indicate that early cumulative exposures of indoor and outdoor air pollution contribute little to nothing to asthma up to 18 years.

Background: Added sugars during early development may influence adiposity, but whether associations vary by developmental timing and child sex is unclear. Objectives: To determine whether child sex modifies associations of added sugars and fructose exposure from pregnancy through 24 months with body composition at 24 months. Methods: This secondary longitudinal analysis included 130 mother-child dyads. Maternal diet was assessed during mid-pregnancy and child diet at 2wk and 6mo (infancy), and 12mo and 24mo (toddlerhood). Multivariable regression tested sex-by-exposure interactions for anthropometric outcomes; 42 children had usable dual-energy X-ray absorptiometry (DXA) data. Results: Prenatal added sugars were more positively associated with percentage body fat and total and regional fat mass in girls than in boys. Prenatal fructose was more positively associated with waist circumference in boys. During infancy, added sugars were more positively associated with percentage body fat and total and regional fat mass in boys, whereas fructose was more positively associated with fat-free mass in girls. Conclusions: Associations of early-life sugars exposure with body composition varied by developmental timing and child sex. Findings from the smaller DXA subset are exploratory and require replication but suggest that susceptibility to early dietary sugars may differ across developmental windows.

The post-ingestive dopamine response is an integral determinant of subsequent eating behavior in animals yet measurement of the post-ingestive response to nutrients in humans has been elusive when assessed in the early post-ingestive period (30 minutes postprandially). We conducted secondary analysis comparing dopamine D2 receptor binding potential (D2BP) measured using [18F]fallypride positron emission tomography in two inpatient controlled feeding cohorts consuming standardized diet (50% carbohydrate; 35% fat; 15% protein) with similar characteristics and procedures but differing in time since last meal: confirmed overnight fast (n=57; 66.7% female; BMI 29.6{+/-}7.6 kg/m2; 31.9{+/-}7.2 years old) and 2-hours after a standardized meal reflecting 20% of energy requirements (n=43; 48.8% female; BMI 28.8{+/-}7.8 kg/m2, 31.3{+/-}7.7 years old). Compared to the fasted cohort, the 2-hour postprandial cohort exhibited significantly reduced whole striatal D2BP (p<0.0001) as well as in clusters in insular cortex, prefrontal cortex which remained after adjustment for age, sex, and insulin sensitivity. Voxelwise comparisons of the relationship between D2BP and BMI in the fasted and fed cohorts reveals clusters within dorsolateral and ventral striatum where dopamine level is dependent on postprandial state and adiposity. Given the similarities between protocol procedures and participant characteristics, our results suggest that the post-ingestive dopamine response to nutrients may be prominent in the extended post-ingestive period and warrant investigation within-subject.

Healthy diet across adulthood is associated with better late-life cognition, but how life-course diet quality relates to brain integrity, and whether brain measures mediate diet-cognition associations, remains unclear as studies with long-term diet records and detailed neurocognitive measures are lacking. We studied 892 participants from the SG70 study, nested within the Singapore Chinese Health Study, with adherence to the Dietary Approaches to Stop Hypertension diet (DASH) assessed between 1993--2025. Dietary quality during midlife, ages 44--55 years, and early elderhood, ages 61--73 years, was examined in relation to seven cognitive domains, brain morphometry, white matter hyperintensities and free-water MRI markers in late life, ages 68--82 years. Higher DASH adherence at both life stages was significantly associated with better late-ife verbal memory, and remained so when both life stages were modelled jointly. Higher midlife DASH adherence was associated with greater white matter volume in association tracts, whereas higher early-elderhood DASH adherence was associated with lower white matter hyperintensity (deep basal ganglia and anterior periventricular regions) and lower frontal and occipital grey matter free water, suggesting lower neurovascular and inflammatory burden. Mediation analyses indicated that white matter volume accounted for 12.3% in mediating the midlife DASH--verbal memory association, while cortical free water accounted for 12.5% in mediating the early-elderhood DASH--verbal memory association. Importantly, participants whose DASH adherence improved from lower adherence in midlife to better adherence in later life showed better verbal memory and more favourable brain integrity than those with persistently low adherence. These findings identify midlife and post-midlife diet quality as modifiable life-course exposures associated with late-life cognitive resilience through differences in macrostructural and microstructural brain integrity.

Background Psychiatric diagnoses and psychotropic medication use among children, adolescents, and young adults have increased in high-income countries, with concerns about geographic variation. We described national trends and geographic variation in Denmark from 2010 to 2025 and developed an interactive online tool to explore these patterns. Methods We conducted a nationwide, descriptive, repeated cross-sectional register-based study of all Danish residents aged 0-24 years in 2010-2025 (n=2,930,744), using the Danish National Patient Registry and the Danish National Prescription Registry. We estimated annual incidence, prevalence, and, for selected diagnoses, lifetime prevalence, by age and sex, and age- and sex-standardised rates across regions, health councils, and municipalities. We assessed geographic variation using deviations from national means, coefficients of variation, Gini coefficients, and funnel plots. Findings Psychiatric diagnoses and psychotropic medication use increased from 2010 to 2025. The annual prevalence of attention-deficit hyperactivity disorder (ADHD) increased from 0.41 to 2.3 per 100 individuals, autism spectrum disorders from 0.20 to 1.2, and melatonin use from 0.14 to 3.0. ADHD and autism spectrum disorders were more prevalent among boys and anxiety disorders among girls. Sertraline use was also more prevalent among girls. Geographic variation was observed across diagnoses and psychotropic medications at regional, health council, and municipal levels. For example, lifetime prevalence of autism ranged from 1.3 to 5.9 per 100 across municipalities, and in 2025 regional coefficients of variation ranged from 0.11 (sertraline) to 0.41 (atomoxetine). Results can be explored in the interactive online tool (https://bupstat.sdu.dk/?lang=en). Interpretation Psychiatric diagnoses and psychotropic medication use increased among Danish children, adolescents, and young adults, with marked geographic variation. Descriptive data cannot establish the causes of this variation, but the findings identify areas for further review and support continued monitoring. Funding Best for Us project (www.bedstforos.dk), funded by the Novo Nordisk Foundation (NNF24SA0093635) and the Obel Family Foundation (69348).